View Full Version : loose knots

02-04-2017, 01:47 PM
I seam to be stuck having a few loose knots on the planking (white pine) What is the best way of dealing with them. Can I pop them out and glue them back in with epoxy?

02-04-2017, 01:54 PM
No, use a similar piece of clear wood, same thickness and grain orientation. I would clean off the edges surrounding the knot, in the parlance of the oncologists, you want to work from clean margins.

Peerie Maa
02-04-2017, 01:56 PM
I believe you had better pop them, clean up the hole with a round rasp to remove any traces of dead bark, and then glue in a plug with the grain oriented so that swelling will not split the board.

Peerie Maa
02-04-2017, 02:10 PM
There is more :D

Sorry I missed this. I am not sure at this point what I'll be using as a seam compound. Jamestown sells something called "seam compound" which sounds like it would fit the bill. I believe that traditionally a mixture of white lead paste and common putty was used. That sounds pretty toxic to use though, and I'm not sure how to source white lead. The Pardey's used 5200. I will not be using that for a number of reasons, but there may be something in that family that could be appealing. Bud McIntosh is mum on the topic. So I'm just not sure yet which way I'll go. I guess I'm leaning towards the Interlux Seam Compound unless someone scares me away from it.

The fitting of the port tuck strake is ongoing, but I don't have many photos of it. What I do have is some documentation of fixing defects in planking stock that I though I'd share.


So here is a spike knot that I want to remove from the plank. A small dutchman was cut out with a very slight bevel and traced. The bevel makes it wider at the top than the bottom so that it snugs up tightly.


Here the knot has been chiseled out and the hole only needs some final smoothing before glue.


The dutchman is glued in with thickened epoxy. I also spread some over the nearby area of tearout that the knot caused in the thickness planer. A few strokes of the handplane and this area is as good as new.

There are other types of fixes as well. Here is a pin knot that I drilled out and replaced with a homemade dowel. The dowel is cedar and is formed by planing it to rough shape and then driving it through a hardwood block with a hole drilled in it. The same bit is used to drill the knot out of the planking and then the plug is glued in with epoxy. It works well.


It is not possible to get perfect planking stock for an entire boat. Even if cost is no object I consider it irresponsible and wasteful. It is not difficult to make permanent repairs in this age of epoxy and it allows the use of second quality stock. The stack of fencing cedar at home depot is probably not up to the job, but it isn't necessary to insist of only building with clear old growth either.

02-04-2017, 02:29 PM
Here is what I have done for "black knots". I first made a tapered ream, with a piece of hacksaw blade (flat side) as the cutter surface.

https://im1.shutterfly.com/media/47b8df10b3127ccec36bf001403000000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025736337.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

ream from the outside (that way if it loosens it will go farther in and not fall out.)
https://im1.shutterfly.com/media/47b8df10b3127ccec36af42ce16300000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025736541.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

https://im1.shutterfly.com/media/47b8df10b3127ccec36b6f2d81fb00000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025736789.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

Turn a tapered plug of the same wood (Jersey white cedar here)

https://im1.shutterfly.com/media/47b8df10b3127ccec36a66e260d400000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025737151.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

Glue in place

https://im1.shutterfly.com/media/47b8df10b3127ccec36a5e31e12b00000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025737417.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

https://im1.shutterfly.com/media/47b8df10b3127ccec36b922fc11f00000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025737839.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

02-04-2017, 02:31 PM
Sometimes cedar a quite a few knots.

https://im1.shutterfly.com/media/47b8df10b3127ccec36a81d2a13f00000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025738823.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

Then trim off.

https://im1.shutterfly.com/media/47b8df10b3127ccec36a2989200000000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201025739809.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

I have seen a variety of things use to plug black knots, ......... even corks. (The same ones used to cork bottles.)

Gib Etheridge
02-04-2017, 04:23 PM
It was a long time ago, but as I remember it:

I needed to drill then plug a bunch of 2" counterbores in some big beam construction. The counterbores were easy with a Forstner bit, but getting 2" plugs that matched perfectly was a bit of a challenge.

I used a 2.25" hole saw to cut out a disc/plug. It was too small so I ground the set out of the teeth that were set to the inside, a little at a time until I got plugs that fit perfectly.

Then there was the problem of the mandrel hole in the middle of the plugs. I drilled each plug just a little ways, just enough to provide a full circle deep enough to act as a guide, then removed the drill bit (mandrel), broke it off short and put it back in and sawed the rest of the way thru. Flipping each plug over left the face with no mandrel hole exposed. All of the plugs were made from cut-offs of the beams they were applied to for a nearly perfect match.

02-05-2017, 11:15 AM
Can you saturated the knot with epoxy and expect that to hold. Or could you apply a glass mat over the knot hole on both sides of the plank and then feather it out? I am planning on painting the hull

Gib Etheridge
02-05-2017, 11:47 AM
Shrinkage in the planking is the problem. This is especially the case with flat grained pine.

If you use plugs cut from the same board and with the same grain orientation it should shrink and swell at about the same rate as the rest of the board and avoid splitting. If you were to glue the plug in with the grain across (perpendicular to) the grain of the board, when the board shrinks, and it will, the plug won't shrink in the same direction and the board will crack.

If you add too much of any non-shrinking substance, for instance epoxy, the same thing will happen. If you're looking to save labor by just filling perhaps you can just use a putty knife to smear in something relatively soft like acrylic latex caulk.

02-06-2017, 07:59 AM
How about using a butt block behind the knot. Maybe 4 to 5 times the size of the hole??????

02-06-2017, 08:18 AM
How about using a butt block behind the knot. Maybe 4 to 5 times the size of the hole??????

I have actually seen that done, and it will work. However the knot may well loosen up over time and fall out. (At least you won't have a hole in the boat, just in the plank.

02-06-2017, 08:27 AM
Thanks for all your help

02-06-2017, 09:07 AM
I will say that a wooden 'tingle' (like a butt block) on the inside is along the lines of a down and dirty working boat solution, but it does work.

Ian McColgin
02-06-2017, 11:04 AM
I keep glancing at this thread title thinking Vince needs to chime in.

02-06-2017, 12:20 PM
I've learned (expensively) how loose knots in any type of wood can break planer blades. Gawd, be careful with that!